I want to buy an HD web camera to Skype with family and friends. My current laptop cam is terrible, but I want to make sure that before I buy a new cam my connection can handle it.
So - what is the minimal upload speed needed to broadcast in 720p?
Is there any other question that I'm not asking myself?
Skype says you need a minimum 1.2 megabit/sec on your upstream and another 1.2 megabits/sec for the downstream. The recommended bandwidth is only 1.5 mbps. Pretty remarkable if it actually looks good.
For reference a 1080p Blu-ray is usualy 20+ mbps, HDTV is usually at least 10+mbps, 720p x264 movies are usually around 3-5 mbps.
Skype will adapt to almost any upload speed; it has very good scalability by reducing the audio and video bit rate / quality to make sure the connection doesn't drop.
So, you can expect Skype to be able to transmit even at a few hundred kilobit/s—not impossible with its codecs. The only question is whether the quality will still be acceptable to you or if it just degrades to a point where you'd rather want to stop video calling altogether.
I'm also quite sure that Skype wouldn't transmit actual 720p video if it didn't have enough bandwidth to maintain a stable connection.
As slhck has pointed out, skype is adaptive.
However, I did manage to find some rough numbers. Skype is said to handle 30fps 720p video. Assuming it's encoding in something like H.264 then you'd be looking at something of the order of 4-5Mbps upload. (EDIT: apparently skype uses googles VP8 video codec.)
In any case, even on a lower resolution system you'll find the HD camera provides a much clearer picture to the other side.
See these links for more info:
How much bandwidth does skype need
EDIT: Googled around about VP8. Apparently it's only advantage is that it's royalty free, unlike H.264. Other than that, VP8 is inferior in both picture quality and bitrate. :-( Still, you probably wouldn't notice the difference. You'll still need approximately 5MBit/s at both ends to get a super fantastic image in real time.
